Module: Gtk::CellLayout
- Defined in:
- (unknown)
Overview
Gtk::CellLayout is an interface to be implemented by all objects which want to provide a Gtk::TreeViewColumn like API for packing cells, setting attributes and data funcs.
One of the notable features provided by implementations of GtkCellLayout are attributes. Attributes let you set the properties in flexible ways. They can just be set to constant values like regular properties. But they can also be mapped to a column of the underlying tree model with gtk_cell_layout_set_attributes(), which means that the value of the attribute can change from cell to cell as they are rendered by the cell renderer. Finally, it is possible to specify a function with gtk_cell_layout_set_cell_data_func() that is called to determine the value of the attribute for each cell that is rendered.
# GtkCellLayouts as GtkBuildable
Implementations of GtkCellLayout which also implement the GtkBuildable interface (Gtk::CellView, #GtkIconView, #GtkComboBox, Gtk::EntryCompletion, #GtkTreeViewColumn) accept GtkCellRenderer objects as <child> elements in UI definitions. They support a custom <attributes> element for their children, which can contain multiple <attribute> elements. Each <attribute> element has a name attribute which specifies a property of the cell renderer; the content of the element is the attribute value.
This is an example of a UI definition fragment specifying attributes: |[ <object class=“GtkCellView”>
<child>
<object class="GtkCellRendererText"/>
<attributes>
<attribute name="text">0</attribute>
</attributes>
</child>"
</object> ]|
Furthermore for implementations of GtkCellLayout that use a Gtk::CellArea to lay out cells (all GtkCellLayouts in GTK+ use a GtkCellArea)
- cell properties][cell-properties
-
can also be defined in the format by
specifying the custom <cell-packing> attribute which can contain multiple <property> elements defined in the normal way.
Here is a UI definition fragment specifying cell properties:
|[ <object class=“GtkTreeViewColumn”>
<child>
<object class="GtkCellRendererText"/>
<cell-packing>
<property name="align">True</property>
<property name="expand">False</property>
</cell-packing>
</child>"
</object> ]|
# Subclassing GtkCellLayout implementations
When subclassing a widget that implements Gtk::CellLayout like Gtk::IconView or #GtkComboBox, there are some considerations related to the fact that these widgets internally use a Gtk::CellArea. The cell area is exposed as a construct-only property by these widgets. This means that it is possible to e.g. do
static void
my_combo_box_init (MyComboBox *b)
{
GtkCellRenderer *cell;
cell = gtk_cell_renderer_pixbuf_new ();
// The following call causes the default cell area for combo boxes,
// a GtkCellAreaBox, to be instantiated
gtk_cell_layout_pack_start (GTK_CELL_LAYOUT (b), cell, FALSE);
...
}
GtkWidget *
my_combo_box_new (GtkCellArea *area)
{
// This call is going to cause a warning about area being ignored
return g_object_new (MY_TYPE_COMBO_BOX, "cell-area", area, NULL);
}
If supporting alternative cell areas with your derived widget is not important, then this does not have to concern you. If you want to support alternative cell areas, you can do so by moving the problematic calls out of init() and into a constructor() for your class.
Instance Method Summary collapse
- #add_attribute(cell_layout, cell, attribute, column) ⇒ nil
-
#area ⇒ Gtk::CellArea
Returns the underlying Gtk::CellArea which might be cell_layout if called on a Gtk::CellArea or might be nil if no #GtkCellArea is used by cell_layout.
-
#cells ⇒ GLib::List
Returns the cell renderers which have been added to cell_layout.
- #clear(cell_layout) ⇒ nil
- #clear_attributes(cell_layout, cell) ⇒ nil
-
#get_area(cell_layout) ⇒ Gtk::CellArea
or nil in case no cell area is used.
-
#get_cells(cell_layout) ⇒ GLib::List
A list of cell renderers.
- #pack_end(cell_layout, cell, expand) ⇒ nil
- #pack_start(cell_layout, cell, expand) ⇒ nil
- #reorder(cell_layout, cell, position) ⇒ nil
-
#set_attributes(cell, array) ⇒ nil
Sets the attributes in list as the attributes of cell_layout.
- #set_cell_data_func(cell_layout, cell, func, func_data, destroy) ⇒ nil
Instance Method Details
#add_attribute(cell_layout, cell, attribute, column) ⇒ nil
#area ⇒ Gtk::CellArea
Returns the underlying Gtk::CellArea which might be cell_layout if called on a Gtk::CellArea or might be nil if no #GtkCellArea is used by cell_layout. or nil in case no cell area is used.
#cells ⇒ GLib::List
Returns the cell renderers which have been added to cell_layout.
#clear(cell_layout) ⇒ nil
#clear_attributes(cell_layout, cell) ⇒ nil
#get_area(cell_layout) ⇒ Gtk::CellArea
or nil in case no cell area is used.
#get_cells(cell_layout) ⇒ GLib::List
Returns a list of cell renderers. The list, but not the renderers has been newly allocated and should be freed with g_list_free() when no longer needed.
#pack_end(cell_layout, cell, expand) ⇒ nil
#pack_start(cell_layout, cell, expand) ⇒ nil
#reorder(cell_layout, cell, position) ⇒ nil
#set_attributes(cell, array) ⇒ nil
Sets the attributes in list as the attributes of cell_layout.
The attributes should be in attribute/column order, as in gtk_cell_layout_add_attribute(). All existing attributes are removed, and replaced with the new attributes.